Abstract

The potential evaporation and transpiration is one of the important elements in hydrological cycle that is considered in irrigation sources and agricultural factors. The purpose of this research is the comparison of evaporation and transpiration amount of the around of Sabalan Mountain witrh experimental methods and determining of necessity of wheat irrigated farming. In this research has been used from ecological elements like: the average of daily temprature, the average of minimum temperature,the average of maximum temperature, the average of relative humidity, the average of minimum relative humidity, the average of maximum relative humidity, the average of monthly raining, the average of daily raining in the period of wheat growing, the average of monthly evaporation and transpiration, the average of daily evaporation and transpiration in the period of growing, Sunny times, wind speed in the height of two meters according to m/sec, synoptic stations of the around of Sabalan Mountain ( Ardebil, Ahar, Sarab, Meshgin shar ).In order to estimated the amount of daily, monthly, and annual evaporation and transpiration and the necessity of wheat for irrigated farming, the coefficient of plant, effective raining and the needed irrigation, have been used from NETWAT, CROPWAT Softwares, and the important methods of potential evaporation and transpiration like: Thornthwaite, Blany- Criddle, Hargreaves – Samani, Penman, Penman – FAO, Penman – monteith. The result represented that the Penman – Monteith method is important with regard to other studied methods in estimating of evaporation and transpiration, and the amounts of evaporation and transpiration of stations in the studied area are different from each other and the raining of each of stations, especially effective raining for wheat with irrigated farming in the station of Ardebil, Ahar, Sarab and Meshgin Shahr represents in order 71 percent, 85 percent, 82 percent and 84 percent.